->''"So what now, Jack Sparrow? [[SealedEvilInADuel We be two immortals locked in an epic battle until Judgment Day when trumpets sound]]?"''
-->-- '''Captain Barbossa''', ''PiratesOfTheCaribbean: The Curse of the Black Pearl''

A MutualDisadvantage is a scenario in which two (or more) sides in a fight are unable to gain an advantage over each other due to both being equally disadvantaged against one another in either offensive or defensive abilities. This can come in two flavors;

* '''[[PaddedSumoGameplay Mutual Invulnerability]]''': Both participants are offensively disadvantaged - neither of them can harm the other, as they are both immune or resistant to each others' attacks. The result is a battle between two {{Stone Wall}}s, making for a stalemate unless and until someone else intervenes.
* '''[[RocketTagGameplay Mutual Weakness]]''': Both participants are extremely susceptible to each others' skills, essentially making it a fight between {{Glass Cannon}}s. The result is either a standoff wherein both sides try to avoid MutuallyAssuredDestruction, or a fight that could go either way, but is very likely to [[CurbStompBattle be one-sided]] in favor of whoever gets the first strike. Compare MexicanStandoff, where the stalemate is the result of the participants all being perfectly matched. Often happens in fights against {{Evil Counterpart}}s.

Note that any RPG system with pair-based ElementalRockPaperScissors will naturally display both types, with equal elements creating mutual invulnerability while opposing elements have mutual weakness.

LikeCannotCutLike and TakesOneToKillOne are {{Sub Trope}}s.

----
!!Mutual invulnerability:

[[foldercontrol]]

[[folder: Anime and Manga ]]

* In ''Manga/{{Bleach}}'', Hitsugaya and Halibel were both capable of transforming each other's attacks into their own, resulting in repeated [[NoSell No Sells]] against each other throughout much of their battle.
* In ''OnePiece'', Smoker and Ace proved unable to hurt each other, due to both being Logia Devil Fruit users with elements that do not naturally interact - Ace's flames equalized with Smoker's smoke - all they achieved was a huge pillar of smoke and fire. It happened again when Ace fought Kuzan and their respective fire and ice Devil Fruits powers nullified each other.
** Kuzan and Sakazuki fought for ''ten'' days on the island Punk Hazard to a stalemate because their Devil Fruits were opposing elements, ice and magma. In the end, they had used their powers so much the halves of the island inhabited by them got permanently altered into a frozen tundra and a volcanic wasteland. [[spoiler:Sakazuki eventually crippled Kuzan and won the battle.]]
* In ''Manga/FairyTail'', the fight between Natsu and Totomaru starts out this way. Totomaru has power over all flame, allowing him to redirect Natsu's attacks, and Natsu is not only immune to fire [[FeedItWithFire but eats it to restore his strength]].

[[/folder]]

[[folder: Comics ]]

* An issue of ''Billy Batson and the Power of Shazam''; [[{{Shazam}} Captain Marvel]] and BlackAdam are evenly matched and cannot harm each other; likewise [[DistaffCounterpart Mary Marvel]] and Black Adam Junior seem to be immune to each other's punches. [[spoiler:But Black Adam Junior '''can''' injure Captain Marvel.]]
* Havok and ComicBook/{{Cyclops}} in ''ComicBook/{{X-Men}}'' comics. As they are brothers, this situation happens very rarely, but when it does, they are both immune to each other's attacks, because their powers work in the same way, and each can use the other's attack as an energy source. The same is true of Sean Cassidy (Banshee), and his cousin Thomas, neither's powers can affect the other. This is believed in both cases to be due to their genetic relationship and can apply to other related mutants as well.
* In a [[MarvelComics Marvel]] / [[DCComics DC]] crossover between Franchise/{{Batman}} and CaptainAmerica, after SelfDemonstrating/TheJoker becomes [[EvenEvilHasStandards furious]] after finding out that his collaborator the RedSkull is a Nazi, the two villains try to use their own weaponized toxins on each other to no effect. Since both Joker and Red Skull are immune to their own toxins and both Joker Venom and Red Skull's "dust of death" are remarkably similar, both characters are also immune to ''each other's'' toxins.

[[/folder]]

[[folder: Film ]]

* Barbossa and Jack Sparrow fall into a mutual invulnerability version of this trope for a short while, during ''PiratesOfTheCaribbean: Curse of the Black Pearl''.
** Again in the third film, though here imposed by terrain. Calypso hated both ships and their captains, so she created a huge typhoon that made maneuvering impossible (removing the Black Pearl's speed advantage) and made firing the cannons impossible (removing the Flying Dutchman's firepower advantage). Thus it came down to a brutal ship to ship fight between crews she hoped neither would survive.
* In the final ''Film/TheMatrix'' movie Neo has fully embraced his 'The One' status and therefore can do just about anything in the Matrix and can withstand an almost limitless amount of damage. Agent Smith has infected everyone, human or machine, in the Matrix and can also do anything and withstand anything.
* ''TheGoldenVoyageOfSinbad''. The eternal battle between Good and Evil is personified by a combat between a griffin and a centaur at the Fountain of Destiny. Neither one can prevail on its own, but "The deeds of weak and mortal men can tip the scales one way or the other."

[[/folder]]

[[folder: Literature ]]

* ''[[Literature/{{Animorphs}} Megamorphs]]'' #2: The crab aliens can't get to the ant aliens' base without getting shredded by their energy weapons, the ants can't penetrate the crabs' force field.

[[/folder]]

[[folder: Live Action TV ]]

* In an episode of ''Series/StarTrekVoyager'', the ship's doctor, a hologram-based artificial intelligence, encounters another such computer program that has become unhinged. When it strikes out at the Doctor's holographic image, the Doctor merely flickers. To demonstrate the futility of the situation, he tosses a nearby object at the other program, who also flickers. "This could get tedious." However, the other program then simply strikes the Doctor's portable holoemitter, knocking it off of him and deactivating him.
* In one episode of ''Series/{{Charmed}}'' Piper and Cole have a fight while both are invulnerable; Piper because [[GooGooGodlike her obscenely powerful unborn child]] was protecting her with a forcefield, and Cole because of the [[NighInvulnerable Nigh Invulnerability]] he acquired as part of the powers he absorbed while in the demonic afterlife. It took Leo chastising them on the pointlessness of their battle to end it.
* In an episode of the ''{{Superman}}'' TV-series, some random dude off the street ends up with a carbon-copy of Superman's powers due to [[LightningCanDoAnything lightning]]. Said random dude then starts a Hero For Hire business, charging people premium rates for applying his superhuman powers, in between using his X-ray vision to [[PowerPerversionPotential check out girl's changing-rooms]]. Supes gets fed up with this pretty quickly and starts actively interfering in the 'business' (and pleasure), causing the dude to lose his temper and start a fight. Both of them, of course, are super-strong, but entirely invulnerable - and they're more invulnerable than super-strong, resulting in a mutually invulnerable brawl... the only possible loser being the surrounding area.
* ''Series/{{Caprica}}'' at one point had Zoe and Tamara fighting in V-World. In this case, they can hurt each other all they want, but neither of them can die since they're both digital avatars. The fight only ended when Zoe talked Tamara into an alliance.
* Battles between Ascended beings usually work out this way in the ''Franchise/StargateVerse''. Since they're EnergyBeings of equal stature, neither one can do anything to ''over''power the other, but they can keep the other sufficiently distracted as to be unable to do anything else. Both Anubis and Adria are taken care of by getting locked into an eternal fight with another Ascended.
** It is implied that Ascended beings can kill one another but only if one is vastly more powerful than the other, which is a very rare case but not impossible: belief can empower an Ascended which is why they insist to everyone on the mortal plains that they're not gods. That was one of the causes for the ideological split between the Alterans and the Ori: the latter formed [[PathOfInspiration Origin]] [[AGodAmI specifically to gain even more power]] but the distance between the Ori galaxy and the Milky Way meant they were still too weak to overpower the Alterans... which is why they started converting the Milky Way's native population to Origin as well, abusing the Alterans' PrimeDirective to build up a power base in plain sight without a DeusExMachina to fear from.

[[/folder]]

[[folder: Professional Wrestling ]]

* In {{Wrestling/ECW}} Rob Van Dam and Jerry Lynn usually started their matches with a series of Chain Wrestling moves which the other countered pretty quickly.

[[/folder]]

[[folder: Real Life ]]

* England vs. Louis XIV's France, ignoring the participation of Austria & co. for a moment. England had a very large, good navy and a tiny army; France had a large, okay-ish navy and a very large, decent-to-good army. Rinse and repeat right up to the end of the Napoleonic Wars. Britain vs The Dutch was the reverse, however; Holland had a ''tiny'' army, but Britain's navy was unable to get its act together for the most part. If there was a narrative pattern to Britain's participation in wars, it'd be having a great big navy that protects it from foes with great big armies - but, conversely, doesn't allow it much chance to really take the war to its land-based foes.
* A mention of the Peloponnesian War could probably go along with that France/England Hundred Years War example. Athens was a sea power and Sparta had the best land forces in Greece. Sparta had to build a navy before it could successfully choke off Athens, almost 30 years in.

[[/folder]]

[[folder: Tabletop Games ]]

* In ''TabletopGames/DungeonsAndDragons'' edition 3.5, Damage Reduction involving alignments were included. There is a lot of infighting between demons and devils both between the two species and [[ChronicBackstabbingDisorder within their own ranks]]. However, high level demons and devils tend to have a lot of damage reduction, which can only be overcome with weapons that have the Good subtype. The same is true for Celestials vs Celestials, but they're less likely to fight.

[[/folder]]

[[folder: Video Games ]]

* In ''VideoGame/TeamFortress2'' this is the case with a few of the classes.
** Two Pyros will fall into this trope. Both are resistant to each other's signature ability (setting each other on fire), their unlockables are useless as the Flare Gun and Axtinguisher require their opponent to be on fire , meaning the winner is decided by either shotguns (if either has one equipped), flamethrowers (which would require either participant to move into the range of the other's flamethrower) or melee weapons (which do have some advantages over each other but don't make all that much difference).
** Demomen equipped with the Chargin' Targe might also qualify (since it increases their resistance to explosives and removes their ability to ambush enemies with sticky grenades).
** Engineers, as the most 'turtle" class, fall into this category as well, apart from a few equipment mismatches.
* In ''{{Pokemon}}'', many elemental types ([[FireIceLightning fire, electric, ice]], and so on) are resistant to attacks of their own element (receiving half normal damage). Bug and Fighting types are resistant to each other's element, and Normal and Ghost types are completely ''invulnerable'' to the other's element. Oddly Ghosts and Dragons are weak to their own element! A fight between such types, especially at low levels (where they're unlikely to know any other attacks), will often result in this. Some matchups involving Dual types can also cause mutual weakness.
** Wobbuffet is another example, as it learns no direct attacks whatsoever and is capable only of various {{Counterattack}}s. Pitting one Wobbuffet against another Wobbuffet will result in a stalemate where neither one can harm the other in any way (and in Generation 3, neither could be switched out for another fighter due to the opponent's ability). However, once they both deplete their PP (which is going to be ''a while'') they will be forced to use Struggle. If they both held Leftovers, the damage taken from struggling was mostly negated, making the battle endless. This was rectified in Generation 4.[[note]] In Diamond/Pearl, using Struggle causes 1/4 of the user's max HP in recoil to the user, meaning any Pokemon with no remaining PP will faint quickly. Its ability was fixed so that it is negated if the opponent also has it.[[/note]]
** Pit two Smeargles together and they can't do anything except futiley try to copy each other. Fortunately unlike with the Wobuffet case, they only have 1PP, so they start struggling quickly.
** And we musn't forget Ditto. Its only move is the ability to transform into the opponent, copying their appearance, stats (barring HP), and their moveset. Now, let's pit two Dittos against each other...
** Catch a Metapod/Kakuna, and they will only know ''Harden''. Pit them against another such enemy, and watch the epic contest unfold, just like in one of the early episodes of [[Anime/{{Pokemon}} the anime]].
* In ''VideoGame/EscapeFromMonkeyIsland'', you engage in a giant statue fight with the villain. Your life bars regenerate too fast for either side to win, so you have to figure out an alternate means to proceed.
* In ''VideoGame/{{Touhou}}'', mortal enemies Mokou and Kaguya, while not invulnerable as such to each other's attacks, are both immortal and will regenerate the wounds inflicted by the other. The result is a long-term stalemate where no matter who wins the individual battles (usually Kaguya), either of them will be back to start again in no time.
* Knalgan [[MirrorMatch mirrors]] in ''BattleForWesnoth'' - a mirror match with a faction composed of highly defensive and slow dwarves, and fast but low-damage or frail outlaws. Neither side has and magic or poison needed to dislodge the other's defensive dwarves, and neither side has any Time-of-Day based powerphase advantage over the other. As a result, neither side has much incentive to attack.
* In the vast majority of {{MMORPG}}s there's the quintessential healer vs healer "battles". Extended in some cases when defensive non-healing classes and setups have some mean of regeneration and extreme defense (as opposed to healer's low defense and extreme regeneration).
* Protoss/Protoss and Zerg/Zerg {{Mirror Match}}es in ''Starcraft2'' are currently like this. Both tend to result in either one player losing almost instantly to a savvy rush (mutual weakness, more often in [=ZvZ=]) or both turtling massively for an excruciatingly long period until one makes a small mistake - and loses almost instantly (mutual invulnerability, more often in [=PvP=]). Terrans have a comparatively vast range of options for breaking a stalemate.
* [[http://www.youtube.com/watch?v=AUGCpClNgwQ This video]] should be a good demonstration of why holding a MirrorMatch between two [[VideoGame/FinalFantasyV Exdeath]] players in the ''DissidiaFinalFantasy'' series is a bad idea.
* In ''VideoGame/TheLegendOfDragoon'', each element takes double damage from it's opposite: [[PlayingWithFire fire]]/[[MakingASplash water]], [[BlowYouAway wind]]/[[DishingOutDirt earth]], [[LightEmUp light]]/[[CastingAShadow dark]]. The sole exceptions are [[ShockAndAwe lightning]] and [[InfinityPlusOneElement neutral]]

[[/folder]]

[[folder: Webcomics ]]

* The titular characters of the webcomic ''BobAndGeorge'' were immune to each others' powers due to being brothers. This is in turn a reference to [[Franchise/{{X-Men}} Scott and Alex Summers]] being immune to the other's superpowers for the same reason.

!!Mutual weakness:

[[/folder]]

[[folder: Film ]]

* In ''Film/{{Star Trek II|The Wrath of Khan}}'', the still badly-damaged ''Enterprise'' leads the less-damaged ''Reliant'' into the Mutara Nebula. When Saavik points out that the nebula will disable shields and sensors on any ship that enters, Spock answers "Sauce for the goose, Lieutenant. The odds will be even."

[[/folder]]

[[folder: Live Action Television ]]

* On ''Series/TheBigBangTheory'', Sheldon and Barry compete over who gets a new office. Since there is not much either one is equally good at, they decide to settle it at something they are equally bad at - namely, sports. So they head to the gym to play a one-on-one basketball game. Unfortunately, they are so equally bad at it that neither one can score a single basket. Eventually, they settle on bouncing a ball in the air and whoever bounces it higher gets the office. Sheldon wins by sheer luck. ("Who's unsatisfactory in P.E. now?")

[[/folder]]

[[folder: Video Games ]]

* Also in the ''{{Pokemon}}'' series, Ghost- and Dragon-typed Pokémon are notably vulnerable to their own element, especially the Dragons as they are the only element that Dragon-type attacks get an advantage against at all (at least, until the introduction of the Fairy-type in the 6th generation). It is also common competitive practice to teach a given Pokémon moves from other elements specifically to counter the types they are weak against (such as giving a Fire-type user the Grass-type "Solarbeam" for use against Water-, Rock- and Ground-types).
** Due to the complicated nature of ElementalRockPaperScissors, Pokémon with dual elemental types can in fact become vulnerable to one of their own elements (like the Rock+Flying Aerodactyl being vulnerable to Rock attacks, or the Fighting+Steel Lucario being vulnerable to Fighting attacks).
** When you start dealing with dual-typed Pokemon, there are a lot of possible matchups between different Pokemon that are weak to one of their opponent's types and strong against another (like the Dark/Fire Houndoom versus the Water/Ghost Jellicent - Water beats Fire and Dark beats Ghost).
*** This also happens between the final evolutions of the three starters in [[VideoGame/PokemonXAndY the 6th generation]] to allow each Pokémon an edge over what would ordinarily be their relative superior. Chesnaught is Grass/Fighting, Greninja is Water/Dark, and Delphox is Fire/Psychic.[[note]]Grass beats Water beats Fire, but Fighting beats Dark, Dark beats Psychic, and Psychic beats Fighting.[[/note]]
** VideoGame/PokemonDiamondAndPearl's use of dual-typed starter Pokémon provides an interesting scenario, where each member of the starting trio ultimately acquired a secondary type that could counter the opposing element: Torterra's Ground typing can counter Infernape's Fire, Infernape's Fighting type can counter Empoleon's Steel, and Empoleon's Steel at least removes its normal weakness to Grass (but also adds in a weakness to its Ground). Infernape was still [[GlassCannon the fastest of the bunch]], though, sometimes capable of knocking the opponent out before they could even throw their first attack. As well, Empoleon could easily learn Ice Beam, letting it deal four times normal damage to Torterra, as opposed to the normal two times a regular Grass-type would suffer.
** The Gastly family is interesting in particular in that the only targets they deal super-effective damage to with Ghost-type attacks - that is, Psychic and Ghost - do super effective damage to them as well.
** Water Pokémon are weak to Grass moves. Nearly all Water-type Pokémon can learn at least one Ice-type move, which Grass-type Pokémon are weak to.
* The Undead and Drake [[MirrorMatch mirrors]] in ''VideoGame/BattleForWesnoth'' - most Undead units are vulnerable to the same faction's magical Dark Adept unit and its Arcane damage, and similarly all Drake units are vulnerable to that faction's magical Cold damage dealing Saurian Augur. Both the Adept and the Augur, however, are SquishyWizard units vulnerable to the conventional attacks of their respective faction. The result is Mutual Weakness.
* Class versus Class battles in ''VideoGame/TeamFortress2'' not described above are more of a mutual weakness, coming down to who has the better aim, ping, and/or luck (Sniper wars in particular).
** The Half-Zatoichi deliberately invokes this, as it has a special ability where it will OneHitKill anyone else who also has the weapon out.
* In many ''Franchise/FinalFantasy'' games, the air/wind element is often vulnerable to itself, inflicting greater damage on flying enemies. Also, Fire and Ice elements are usually vulnerable to each other.
* In ''VideoGame/FinalFantasyTactics'' characters could receive attack (or defense) bonuses depending on each fighter's astrological sign -- however, the bonus always applied both ways.
* In the ''VideoGame/DissidiaFinalFantasy'' [[DivineChessboard campaign modes]], the player would sometimes happen upon a golden Manikin piece (generally optional encounters guarding valuable equipment). These units tend to be equipped in such a way that their health is critically low, but are augmented in other ways (such as having nigh impenetrable Bravery defense, or having summons that they immediately use to send their own Bravery points through the roof), meaning that the first HP attack to connect is generally the one that wins the match.
* In ''Franchise/FireEmblem'' Divine Dragon manaketes are specialized in dealing damage against other dragons/manaketes. While Divine Dragons [[AlwaysLawfulGood are never enemy units]] in the main game, both ''VideoGame/FireEmblemShadowDragon'' and ''VideoGame/FireEmblemAwakening'' have a multiplayer where Divine Dragon Manakete units. can face against eachother. The latter also introduces the Taguels who deal effective against all beast units, like the manaketes they're only encountered as enemies in multiplayer spotpass material.

[[/folder]]

[[folder: Real Life ]]

* In RealLife, the concept of idea of [[http://en.wikipedia.org/wiki/Mutual_assured_destruction mutual assured destruction]] is the reason the Cold War "remained cold"; if either the U.S. or Russia launched a nuclear attack, the other side would have enough time to launch a nuclear counterattack and hit the other side just as hard.
** This is still generally the reason ''nobody'' uses nuclear weapons in the modern age: even if you did launch a nuke at somebody else, they'd just lob a nuke right back before yours got there, and then you'd both be dead.
** This also served as the central conflict in the film ''WarGames'' when the WOPR supercomputer (with access to real nukes) was instructed to play a simulation called "Global Thermonuclear War". In the end, it memorably declared "The only winning move is not to play."
* Any duel with lethal weapons where the participants are not wearing armor can become this, especially if the weapon style is focused on offense. For example, a LOT of serious rapier duels ended with either two people dead, or one dead and one crippled.


!! Pair-based systems

[[/folder]]

[[folder: Tabletop Games ]]

* In ''TabletopGame/DungeonsAndDragons'' 3rd edition:
** Fire/Cold, [[GoodHurtsEvil Good]] / [[AllergicToEvil Evil]] and [[OrderVersusChaos Lawful/Chaotic]] effects are particularly effective against creatures who embody the opposite element, and do not affect creatures who embody the same element. A creature who is both Good and Evil or Lawful and Chaotic (such as a FallenAngel or AscendedDemon) gets both sets of vulnerabilities, but a creature who embodies both Fire and Cold is immune to both.
** Living creatures (and [[{{Eberron}} deathless]]) are powered by positive energy (which heals them) and harmed by negative energy, while [[ReviveKillsZombie undead are affected in the opposite manner]]. Undead who can manipulate negative energy are more common than living creatures who can manipulate positive energy, however.
** Some Air creatures take penalties when defending against Earth effects and vice versa, but this is applied less consistently than the above dualities, largely because Earth and Air rarely exist as PureEnergy.

[[/folder]]

[[folder: Video Games ]]

* ''VideoGame/ChronoCross'' had three sets of opposing elements (Red/Blue, Green/Yellow, Black/White), each dealing increased damage to its opposite and reduced damage to itself; every character in the ([[LoadsAndLoadsOfCharacters rather large]]) roster was assigned an elemental affinity.
* ''VideoGame/FinalFantasyX'' and [[VideoGame/FinalFantasyX2 its sequel]], although the player characters were NonElemental by default, elements were arranged in pairs (Fire/Ice and Water/Thunder) with each doing increased damage to its opposite. The player could also find (or [[ItemCrafting customize]]) weapons and armor with elemental affinities, which could create scenarios of mutual weakness or invulnerability depending on what was equipped at a given time.
* ''VideoGame/TheLegendOfDragoon'' had pairs of opposing elements (Fire/Water, Earth/Wind, Light/Dark) doing increased damage to each other, reduced damage to itself; the Thunder element had no opposite, but also shared reduced damage against itself. Every character (and most monsters) had an elemental affinity, and each character's strongest armor (the "DG armor" series) would completely nullify damage from their own element.
* ''ShadowHearts'' has Fire/Water, Earth/Wind, and Light/Dark. The pairs do increased damage to each other, and there are spells that add elemental status to your weapons. In each game, you acquire one character of each element (and in the second and third game, a NonElemental character); each character's ultimate armor allows them to resist their opposing element.